Summary: At the request of the erythroid biology community, the laboratory has continued its efforts to update and expand the description of erythroid cell genetics in the context of post-genome biology. Previously, we reported the sequencing of human erythroblast libraries to generate an informatic database describing the erythroid transcriptome. Named Hembase (http://hembase.niddk.nih.gov/), the database is comprised of homology comparisons from our Expressed Sequence Tag (EST) collection with sequences contained within other publicly available databases. The current version of the Hembase transcriptome database is organized according to the March 2006 annotation of the human genome. In addition, several disease-related search functions (Blood Groups, Cytoskeleton, Heme Synthesis, Hemoglobin, Hemolysis Related Enzymes) were integrated into Hembase to provide a genome-based organization of erythroid diseases. Based upon the recent discovery of functional RNA molecules that do not encode proteins, the database has been updated to include an undefined category of transcripts that do belong neither to clustered transcriptional foci within the genome nor protein-encoding regions. The database is presented on the worldwide web to disseminate information generated from the laboratory and to introduce the basic and clinical communities with a genome-organized view of erythroid disease. The database updates have been featured in Science and Biotechniques journals.